Keratoconus is a non-inflammatory eye condition in which the normally round dome-shaped cornea progressively thins causing a cone-like bulge to develop. This eventually impairs the ability of the eye to focus properly, causing a reduction in vision. It can be treated using rigid gas permeable contact lenses and requires a corneal graft in around 20% of cases. The corneal endothelium can sometimes be split leading to corneal hydrops. This is an uncommon complication seen in advanced keratoconus, and is characterized by stromal oedema due to leakage of aqueous humor through a tear in Descemet’s membrane.
Another form of treatment is corneal cross-linking. This involves application of riboflavin (vitamin B2) solution to the eye that is activated by illumination with UV-A light for approximately 30 minutes. The riboflavin causes new bonds to form across adjacent collagen strands in the stromal layer of the cornea (cross-links), which recovers and preserves some of the cornea’s mechanical strength. The corneal epithelial layer is generally removed to increase penetration of the riboflavin into the stroma, a procedure known as the Dresden protocol.
People that are considered for treatment must undergo an extensive clinical workup, including corneal tomography, computerized corneal topography, endothelial microscopy, ultrasound pachymetry, b scan, sonography, keratometry and biomicroscopy.
The added strength to the stromal layer helps prevent further progression of the keratoconus in around 90% of cases. In around 45% of cases cross-linking leads to an improvement vision with spectacles or contact lenses.